1. Field of the Invention
The present invention relates to electric fans and more particularly, to a fan biasing transmission mechanism, which controls biasing of the fan head at a low speed.
2. Description of the Related Art
A fan biasing control structure 10 for electric fan according to the prior art, as shown in FIGS. 1 and 2, generally comprises a housing 11 having a first mounting chamber 12 and a second mounting chamber 13, a control rod 14 mounted in the first mounting chamber 12, a driving gear wheel 15 and a driven gear 16 mounted on the control rod 14, a follower gear wheel 17 pivotally mounted in the second mounting chamber 13 and meshed with the driven gear 16, a link 18 coupled with the follower gear wheel 17, a worm 1 coupled to a motor (not shown) and meshed with the driving gear wheel 15 and a cap 19 covering the housing 11. During rotation of the worm 1, the driving gear wheel 15 is driven to rotate the follower gear wheel 17, causing the link 18 to bias the fan head. This design of fan biasing control structure is still not satisfactory in function and has drawbacks as follows: (a) the diameter ratio between the driving gear wheel 15 and the follower gear wheel 17 is 1:1, i.e., the transmission speed maintains unchanged, and therefore the fan head is biased at a high speed; (b) because the driven gear 16 is directly meshed with the follower gear wheel 17 that bears the weight of the fan head directly, torque is directly acted upon the driven gear 16, and therefore the driven gear 16 wears quickly with use.